Make use of generics - Githubissues

Hi, thanks for this library. I'm experimenting with it to represent a tree like structure and seems to fit well.

I think it would be nice to make use of generics for the Node and Tree class, something like:

NodeT = TypeVar("NodeT", bound=Node)

class Tree(Generic[NodeT]):
    def __init__(
        self,
        name: str | None = None,
        *,
        factory: type[NodeT] | None = None,
        ...
    ) -> None: ...

    def add_child(self, child: NodeT | Tree | Any, ...) -> NodeT: ...

DataT = TypeVar("DataT")

class Node(Generic[DataT]):
    def __init__(
        self,
        data: DataT,
        *,
        parent: Node,
        data_id: DataIdType | None = None,
        node_id: int | None = None,
        meta: dict = None,
    ): ...

    @property
    def data(self) -> DataT: ...

    def set_data(self, data: DataT, *, data_id=None, with_clones: bool = None) -> None: ...

I think most of the time people will create trees with the same node class, and with the same data type as well. I can work on a PR if you think this is a good idea.

mar10 / nutree

Make use of generics #8